Calibrating an oxygen sensor of a domestic appliance

Abstract

A method for calibrating an oxygen sensor of a household appliance includes a calibration process which is automatically started when at least one status parameter of the household appliance has at least reached a predetermined threshold value. The household appliance can be a steam cooking appliance, and the oxygen sensor can be a lambda probe.

The invention claimed is: 
     
       1. A method, comprising:
 automatically starting a calibration process for calibrating an oxygen sensor of a household appliance in response to a status parameter of the household appliance reaching or exceeding a predetermined first threshold value; 
 wherein the status parameter comprises a door opening time. 
 
     
     
       2. The method of  claim 1 , wherein the household appliance is a steam cooking appliance. 
     
     
       3. The method of  claim 1 , wherein the oxygen sensor is a lambda probe. 
     
     
       4. The method of  claim 3 , further comprising:
 measuring during the calibration process a pump flow of the lambda probe; and 
 when the pump flow remains for a predetermined time period within a predetermined fluctuation margin, selecting a value of the pump flow from the fluctuation margin as a reference value of the pump flow. 
 
     
     
       5. The method of  claim 4 , wherein an average value of the fluctuation margin is selected as the reference value of the pump flow. 
     
     
       6. The method of  claim 1 , wherein the calibration process is automatically started when a plurality of status parameters of the household appliance have reached predetermined-threshold values, respectively. 
     
     
       7. The method of  claim 1 , wherein the status parameter further comprises a time period elapsing since a last calibration, and the calibration process is automatically started in response to the time period reaching or exceeding a second threshold value, and the door opening time reaching or exceeding the first threshold value. 
     
     
       8. The method of  claim 1 , wherein the status parameter further comprises a cooking chamber temperature and the calibration process is automatically started in response to the cooking chamber temperature reaching or falling below a third threshold value, and the door opening time reaching or exceeding the first threshold value. 
     
     
       9. The method of  claim 1 , further comprising discontinuing the calibration process when the calibration process lasts longer than a predetermined threshold value. 
     
     
       10. The method of  claim 1 , further comprising discontinuing the calibration process when a cooking chamber door of the household appliance is closed. 
     
     
       11. The method of  claim 1 , further comprising:
 storing a result of the calibration process; and 
 evaluating the result for a malfunction of the oxygen sensor. 
 
     
     
       12. The method of  claim 11 , further comprising:
 measuring during the calibration process a pump flow of the lambda probe; 
 when the pump flow remains for a predetermined time period within a predetermined fluctuation margin, selecting a value of the pump flow from the fluctuation margin as a reference value of the pump flow; and 
 using the reference value of the pump flow as the result. 
 
     
     
       13. A household appliance, comprising:
 a treatment chamber; 
 an oxygen sensor; and 
 a data processing device for determining a moisture content in the treatment chamber based on a measured value of the oxygen sensor, said household appliance being configured to automatically start a calibration process for calibrating the measured value of the oxygen sensor in response to a status parameter of the household appliance reaching or exceeding a predetermined first threshold value; 
 wherein the status parameter comprises a door opening time. 
 
     
     
       14. The household appliance of  claim 13 , wherein the household appliance is a steam cooking appliance, with the treatment chamber representing a cooking chamber configured for application of steam. 
     
     
       15. The household appliance of  claim 14 , wherein the status parameter further comprises a temperature in the cooking chamber, and the calibration process is automatically started in response to the temperature in the cooking chamber reaching or falling below a second threshold value, and the door opening time reaching or exceeding the first threshold value. 
     
     
       16. The household appliance of  claim 13 , wherein the oxygen sensor is a lambda probe. 
     
     
       17. The household appliance of  claim 13 , wherein the data processing device includes a memory device configured to store a result of the calibration process. 
     
     
       18. A method, comprising:
 automatically starting a calibration process for calibrating an oxygen sensor of a household appliance in response to a status parameter of the household appliance reaching a predetermined threshold value, wherein the oxygen sensor is a lambda probe; 
 measuring, during the calibration process, a pump flow of the lambda probe; and 
 in response to the pump flow remaining for a predetermined time period within a predetermined fluctuation margin, selecting a value of the pump flow from the fluctuation margin as a reference value of the pump flow. 
 
     
     
       19. The method of  claim 18 , further comprising:
 storing the reference value of the pump flow as a result of the calibration process; and 
 evaluating the result for a malfunction of the oxygen sensor.